The present invention relates to a device for removing pull studs, and more specifically to a socket-type pull stud removal device that substantially increases the level of torque that can be applied to a pull stud, which in turn dramatically increases the ease of pull stud removal and installation.
A large amount of machining today is performed with the assistance of computer-aided equipment. Specifically, computer numerical control (CNC) machines are utilized by a large number of companies that perform any of a wide range of machining applications. CNC machines allow automated machining to be performed while maintaining high precision dimensional tolerancing.
CNC machines use a draw bar to selectively engage one end of a tool holder. The other end of the tool holder contains the desired drilling bit, mill, bore, or other machining tool. Thus, the type of tool holder selected depends upon the type of machining tool that is desired to be used by the CNC machine. The CNC machine also contains a robotic arm, which is known as a tool changer, that performs the automated function of positioning the selected tool holder in an engageable position adjacent the draw bar.
Focusing more specifically on the mounting of a tool holder to a draw bar, the CNC machine engaging end of all tool holders contain a threaded aperture. A small engagement facilitating device, known as a pull stud, includes a threaded shank that rotatably secures into the threaded aperture of a tool holder. In addition to the threaded shank section, pull studs are configured to further include an enlarged diameter section, relatively thin flange section, and an elongated neck section that extends upward from the flange to a knob section at the distal end of the pull stud. Parallel wrenching flats are milled or otherwise formed at diametrically opposite sides of the flange section.
The draw bar of the CNC machine includes an engagement tip which securably grips the knob, elongated neck, and flange sections of a pull stud in order to mount to a tool holder. Since there are many different companies that produce CNC machines, and each company utilizes their own proprietary design, there are several different types of engagement tip configurations. Some engagement tip designs utilize a ball-type mechanism, while others use a clamp and pinch-type mechanism. In addition to the different styles of engagement tip mechanisms, the specific dimensional parameters of the engagement tip mechanisms also vary between CNC machine manufacturers. As a result, several different types of pull studs exist of slightly varying dimensional parameters in order to accommodate the varying engagement tip styles and dimensional configurations.
Due to the high amount of torque that is transmitted through a pull stud from the spindle of a CNC machine, to the tool holder and attached tool, the threaded shank section of a pull stud must be rotatably secured in the threaded aperture of the tool holder at a high degree of torque (on the order of 85 ft. lbs.). This torque is applied to the pull stud at the relatively thin wrenching flats of the flange section of a pull stud. Substantially, the entire remainder of the pull stud outer surface is circular in configuration. Thus, the relatively thin wrenching flats provide the only obvious gripping surface for use in creating a rotational force to remove and install a pull stud from a tool holder.
As such, an open ended wrench (or crescent wrench) is the tool typically utilized for removal of a pull stud. This technique of using an open ended wrench to remove a pull stud has proved most unsatisfactory, since the relatively thin wrenching flats do not provide enough surface area for an open ended wrench to grip the pull stud and produce an adequate amount of torque. The high amount of force that must be used by an operator in attempting to remove the pull stud from the tool holder commonly results in the wrenching flats of the pull stud being rounded or stripped, the wrench being broken, or other disastrous results. This also creates a dangerous situation in which the operator can be injured by the wrench breaking or slipping off of the pull stud while the wrench is attempted to be turned with a large amount of force.
There have been a few minor attempts to produce a mechanism that keeps a crescent wrench-type head from slipping off of the wrenching flats of a pull stud, but these attempts have met with extremely limited success, and as such, have been ignored by the industry as a whole. There is a continuing need in the art for a device that can somehow more securely attach to the exposed portion of a mounted pull stud and dramatically increase the amount of torque that can be generated to facilitate removal of the pull stud from a tool holder.
The present invention is directed towards a device for facilitating removal a pull stud from a tool holder. A pull stud has a knob, elongated neck, flange, and threaded shank section, and secures in a tool holder via the threaded shank section. The pull stud removal device includes a body comprising a top end, a bottom end, and an outer circumferential surface. The top end of the body contains a drive socket cavity that is sized and configured for receival of a drive socket. The bottom end and an outer circumferential surface of the body contain an aperture that is sized and configured for receival of a pull stud. The aperture is circumscribed by a plurality of inner walls that are correspondingly sized and configured to mate with a pull stud. The receival of a pull stud into the device results in the mating of the inner walls of the aperture with the knob, elongated neck, and flange section of the pull stud, thereby substantially increasing the level of torque that can be applied to a pull stud through a drive socket mounted in the drive socket cavity of the device, for tightening and removing the threaded shank section of the pull stud from a tool holder.
In a preferred embodiment of the present invention, the outer circumferential surface of the body of the pull stud removal device is substantially polygonal and comprises at least three sides that have a tool receiving pattern. The aperture penetrates the bottom end and at least one side of the polygonal body. Further, the aperture is sized and configured for lateral receival of a pull stud. Preferably, the inner walls of the aperture correspond in shape to the outer surfaces of a pull stud to provide for selective simultaneous engagement with the knob, elongated neck, and flange sections of a pull stud.
In one exemplary embodiment, the removal device includes a longitudinal axis. The aperture is generally U-shaped in configuration, and extends inward into the majority of the width (the parameter orthogonal to the longitudinal axis) of the device, beyond the longitudinal axis to laterally receive and position a pull stud in substantially the center of the device.
A pull stud to which the device can be attached preferably includes: (1) a threaded shank section; (2) a flange section further including a circular region lower surface, a circular region outer surface, a circular region upper surface, parallel wrenching flats, and a truncated upper surface; (3) an elongated neck further including a fillet region having a fillet radius, and a cylindrical region; and (4) a knob further including a lower chamfered surface, a central circular surface, an upper circular tapered surface, and an upper end. Correspondingly, the bottom end of the body of the device acts as a mating surface that contacts the circular region upper surface of a pull stud, while the aperture inner walls form mating surfaces that contact the parallel wrenching flats, the truncated region upper surface, the fillet region, the cylindrical region, the lower chamfered surface, and the central circular region of a pull stud.
In one preferred embodiment of the present invention, the polygonal body is formed as a single member and has six sides. The top end of the polygonal body of the device contains a drive socket cavity that is sized and adapted to correspondingly mate with a drive socket. Preferably, at least one of the inner surfaces of the drive socket cavity includes a small depression for selective engagement with a drive socket securement detent. Further, the device is constructed of a metallic material, preferably a high-strength steel.
In another aspect of a preferred embodiment of the present invention, the device additionally includes a retaining device for securing a pull stud within the aperture of the device. In one exemplary embodiment, the retaining device is self-locking, and is rotatably actuated by the insertion of a pull stud into the aperture of the device.
In a pull stud removal device constructed in accordance with the present invention, the inner walls of the aperture correspond in shape to the outer surfaces of the pull stud to provide for selective simultaneous engagement of a substantially large surface area between the removal device and the pull stud, thereby dramatically increasing the level of torque that can be applied to a pull stud through a drive socket mounted in the drive socket cavity of the device, for tightening and removing the threaded shank section of the pull stud from a tool holder. This device provides the above stated benefits that were never before achievable using prior art tools such as wrenches.